using System;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.X509;

namespace Org.BouncyCastle.Asn1.Cms
{
	public class KeyTransRecipientInfo
		: Asn1Encodable
	{
		private DerInteger          version;
		private RecipientIdentifier rid;
		private AlgorithmIdentifier keyEncryptionAlgorithm;
		private Asn1OctetString     encryptedKey;

		public KeyTransRecipientInfo(
			RecipientIdentifier rid,
			AlgorithmIdentifier keyEncryptionAlgorithm,
			Asn1OctetString     encryptedKey)
		{
			if (rid.ToAsn1Object() is Asn1TaggedObject)
			{
				this.version = new DerInteger(2);
			}
			else
			{
				this.version = new DerInteger(0);
			}

			this.rid = rid;
			this.keyEncryptionAlgorithm = keyEncryptionAlgorithm;
			this.encryptedKey = encryptedKey;
		}

		public KeyTransRecipientInfo(
			Asn1Sequence seq)
		{
			this.version = (DerInteger) seq[0];
			this.rid = RecipientIdentifier.GetInstance(seq[1]);
			this.keyEncryptionAlgorithm = AlgorithmIdentifier.GetInstance(seq[2]);
			this.encryptedKey = (Asn1OctetString) seq[3];
		}

		/**
		 * return a KeyTransRecipientInfo object from the given object.
		 *
		 * @param obj the object we want converted.
		 * @exception ArgumentException if the object cannot be converted.
		 */
		public static KeyTransRecipientInfo GetInstance(
			object obj)
		{
			if (obj == null || obj is KeyTransRecipientInfo)
				return (KeyTransRecipientInfo) obj;

			if(obj is Asn1Sequence)
				return new KeyTransRecipientInfo((Asn1Sequence) obj);

			throw new ArgumentException(
				"Illegal object in KeyTransRecipientInfo: " + obj.GetType().Name);
		}

		public DerInteger Version
		{
			get { return version; }
		}

		public RecipientIdentifier RecipientIdentifier
		{
			get { return rid; }
		}

		public AlgorithmIdentifier KeyEncryptionAlgorithm
		{
			get { return keyEncryptionAlgorithm; }
		}

		public Asn1OctetString EncryptedKey
		{
			get { return encryptedKey; }
		}

		/**
		 * Produce an object suitable for an Asn1OutputStream.
		 * <pre>
		 * KeyTransRecipientInfo ::= Sequence {
		 *     version CMSVersion,  -- always set to 0 or 2
		 *     rid RecipientIdentifier,
		 *     keyEncryptionAlgorithm KeyEncryptionAlgorithmIdentifier,
		 *     encryptedKey EncryptedKey
		 * }
		 * </pre>
		 */
		public override Asn1Object ToAsn1Object()
		{
			return new DerSequence(version, rid, keyEncryptionAlgorithm, encryptedKey);
		}
	}
}
